This invention relates to a device and method for providing a visual indication of wind speed.
Weather vanes are commonly used to provide a visual indication of wind direction. To date, however, there is no satisfactory known system for providing a reliable and accurate visual indication of wind speed. Baxter U.S. Pat. No. 4,854,579, issued Aug. 8, 1989, discloses one form of a wind speed indicator in which colored indicia are provided on the blades of a propeller, which are spaced apart 180.degree. from each other. The propeller turns under the influence of the wind, and the colored indicia provide the appearance of a colored ring as the propeller turns. The color intensity of the ring is said to vary according to wind speed, and the actual color intensity of the ring is compared to a chart of various color intensities to calculate wind speed. This device is very limited in its ability to indicate wind speed, since only a very rough estimation of wind speed can be ascertained by comparing the color intensity of the ring with that of the chart. Further, variance in ambient light or other conditions not related to wind speed could have an effect on the color intensity of the ring, thus decreasing the reliability of the wind speed indicator.
It is an object of the present invention to provide a wind speed indicator which is capable of indicating a large number of wind speeds above predetermined threshold wind speeds. It is a further object of the invention to provide a wind speed indicator having a construction which provides a reliable indication of wind direction, in which the wind speed indicating components also function to provide an indication of wind direction. It is a further object of the invention to provide a wind speed indicator which is relatively simple in its construction and operation, and which nonetheless provides a reliable indication of wind speed. A further object of the invention is to provide a wind speed indicator which is extremely easy to read, and in which the wind speed indication can be read from a distance.
In accordance with one aspect of the invention, a wind speed indicator includes an impeller which is driven by the wind and a rotatable member drivingly interconnected with the impeller, so that the rotatable member rotates in response to the impeller being driven by the wind. Wind speed indicia is provided on the rotatable member for visually indicating wind speed based on the speed of rotation of the rotatable member. The rotatable member and the impeller are preferably mounted toward opposite ends of a base, which is mounted for pivoting movement between the impeller and the rotatable member. The rotatable member is preferably planar, and acts as a rudder to provide pivoting movement of the base in response to changes in wind direction. The wind speed indicia are preferably in the form of a series of spaced individual indicia having as loci the circumference of a circle, the center of which is coincident with the axis of rotation of the rotatable member. The series of spaced individual indicia provide the appearance of a ring when rotated above a predetermined angular velocity in response to rotation of the impeller as caused by wind above a first threshold wind speed. One or more additional series of spaced individual indicia are also provided on the rotatable member, with each additional series having as loci the circumference of a circle having its center coincident with the axis of rotation of the rotatable member. Each additional series of spaced individual indicia provide the appearance of a ring when the rotatable member is rotated above a threshold angular velocity in response to rotation of the impeller caused by a threshold wind speed. In this manner, one virtual ring is apparent when wind speed exceeds a first threshold, two virtual rings are apparent when the wind speed is above a second threshold greater than the first threshold, three virtual rings are apparent when wind speed exceeds a third predetermined threshold greater than the first and second thresholds, and so on. The first series of individual indicia are located a first distance from the axis of rotation of the rotatable member and are spaced apart at a first spacing. A second series of spaced individual indicia are located at a second distance from the axis of rotation of the rotatable member, less than the first distance, and are spaced apart at a second spacing different than the first spacing. Additional series of individual indicia are located inwardly of the first and second series, with each additional series being located closer to the axis of rotation of the rotatable member than the preceding series, and with the spacing between the indicia in each additional series being different than the spacing between the individual indicia in the preceding series. The spacing between the individual indicia in each series is preferably either incrementally greater than or less than the spacing between the indicia in the adjacent series. This arrangement provides the appearance of successive adjacent virtual rings as wind speed increases.
In accordance with another aspect of the invention, the spaced individual indicia can be provided on the blades of the impeller, which is mounted toward one end of the base. A rudder is provided on the opposite end of the base to pivot the base in response to change in wind direction. In this embodiment, the impeller blades are relatively large, and each presents a relatively wide surface on which several spaced individual indicia are located. This embodiment indicates wind speed by viewing the impeller and determining the number of virtual rings which are apparent when the impeller is rotated by the wind.
The invention also contemplates a method of providing a visual indication of wind speed, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.